The present invention relates to an electric sewing machine comprising at least one regulator for influencing the operation of the stitch-forming instrumentalities, a manual knob operatively connected to the regulator for setting the same to a desired setting, and a single manually operable member for controlling the running and stopping of the machine through an electric circuit for controlling an electric motor.
A sewing machine is already known wherein an amplitude regulator or a feed regulator is set by the operation of a single manual knob to form a desired continuous seam, and a single manually operable member controls, by a shifting operation thereof from outside of the machine, driving of an electric motor through an electric circuit to run or stop the machine. In actual operation of such a machine, however, the operator feels frequently cumbersome in setting the regulator(s) and/or in controlling the machine, for instance, in the case of executing the sewing operation to form a continuous seam including a zigzag seam with a desired amplitude and a desired feed length and/or direction and a non-ravel seam or seams added to the zigzag seam at the beginning and/or end thereof, because the operation has to carry out the setting for non-ravel seaming both on the amplitude regulator and the feed one as well as the operation for running and stopping of the machine, respectively, but without neglecting their mutual delicate relation.
Furthermore, the operator has to, as usual, guide the work fabrics to be sewed along a predetermined seamforming line during the operation. These operations are so cumbersome even for skilled operators to be a cause to neglect the essential non-ravel seaming.